20 percent of their foreign exchange annually. This situation appears to pose no serious problem; nor does shipping, for the food tonnage is only about 15 percent of that of imported fuels. The food imports of the developing countries are much smaller in the aggregate than those of the developed countries, about $6 billion as against $20 billion, but their food imports require about the same 15 percent of their very limited foreign exchange. Unless catastrophic changes occur in the rate of progress shown by the LDC's in the past 15 years, food imports should not be of unmanageable dimensions.* Energy Resources The outlook for energy resources is brighter than that for food. By the year 2000 world consumption of energy will quite possibly be about five times what it was in 1965. World consumption of energy in 2000 at the U.S. level in 1965 appears unattainable even though rates of increase in nearly all other parts of the world, and especially in the less developed areas, are expected greatly to exceed that of the United States during the next 30 years. The extrapolation of recent trends in energy consumption in the world does indicate that by the end of the century world consumption could be above the levels obtained in western Europe in 1965, with only Africa falling much below this level. (See Table 2.) Will reserves be adequate for such an expansion of consumption? World reserves of fossil fuels (coal, oil, and gas) are estimated at 3 to 4 trillion tons of coal equivalent. This is about 500 times current annual consumption, and about 100 times the rate of consumption projected for the year 2000. Additional energy will be available from fissionable materials, for which reserves are estimated to contain several times as much energy as reserves of the fossil fuels, assuming that "breeder" reactors can be perfected. If fusion reactions using hydrogen are developed, they are expected to open up energy resources many times those of fossil fuels or fissionable materials. Minerals Reserves of the major metallic minerals, such as iron, aluminum, manganese, and copper must also be assessed. New discoveries, resort to lower-grade ores, and improvements in mining and processing should make it possible to support a growing population and an increasing industrialization during the coming decades. Reserves of metals are not as well known as those of energy materials, but it is clear that available quantities of iron, aluminum, and manganese will supply all projected needs for the next several decades at little increase in cost, and that more remote or lower-grade reserves can cover all *See also T. W. Schultz, "The Food Supply-Population Growth Quandary," in this volume.rbons reported "used in or sold to agriculture" in 1966 were taken from the U.N. F'ood and Agriculture Organization's Production Yearbook 1967 (7, Tables 143-148), although in most cases they appeared to be incomplete.